Mullerian Inhibiting Substance is produced by the mammalian fetal testis and results in regression of the Mullerian duct, the anlagen of the uterus, fallopian tube, and upper vagina. The underlying hypothesis of this proposal is that a fetal repressor which initiates morphogenic dissociation of an organ system in the embryo may produce the same effects against tumors derived from the cell types which respond to the fetal regressor in embryonic life. MIS is detected by a modified semi-quantitative organ culture assay. Using the bone newborn testis as a postnatal source, MIS has been partially purified. Sequential dialysis, ultrafiltration, anion and cation exchange chromatography, and carbohydrate affinity chromatography has resulted in a 7,000-fold purification. Total mRNA has been extracted from bovine newborn testis and translated in a rabbit reticulocyte lysate system. Using hybridoma techniques, we have developed a monoclonal antibody to MIS which blocks biological activity. A fraction with biological activity can then be eluted from a HAS Sepharose column in NH4SCN. Immunoabsorbant techniques will be used to purify MIS to homogeneity and to identify reticulocyte lysate translations. MIS mRNA will then be enriched, a cDNA and double stranded DNA produced, and a plasmid transfected into E. coli for cloning and MIS production. The MIS DNA will then be sequenced and the amino acid sequence of the preprocessed MIS inferred. Using the monoclonal antibody a radioimmunoassay for MIS will be developed. A monoclonal antibody will be raised to MIS receptors, again using hybridoma techniques. Ultrastructural studies of the regressing Mullerian duct show breakdown of the basement membrane and, in addition to epithelial death, migration and transformation of the epithelial cells into the surrounding mesenchymal compartment. Glucosaminoglycan analysis of the ducts during regression show an increase in hyaluronidase activity associated with a fall in hyaluronic acid. Urogenital ridge matrix constituents such as glucosaminoglycans, glycoproteins, and collagen will be further characterized and the role of MIS in this embryonic regulation studied. MIS is cytotoxic to an ovarian cancer in monolayer microcytotoxicity assay and inhibitory to colony growth in a soft agar colony inhibition assay. Other tumors will be studied in this assay and in in vivo animal systems, to (Text Truncated - Exceeds Capacity)